1. Field of the Invention
The present invention relates to a technique for drawing three-dimensional graphics. More particularly, the present invention relates to an apparatus and a method for drawing three-dimensional graphics by converting two-dimensional polygon data to three-dimensional polygon data, and a recording medium having the three-dimensional polygon data recorded therein.
2. Description of the Background Art
Recently, in order to enable output of realistic and delicate images on a car navigation system and the like, three-dimensional graphics drawing apparatuses performing three-dimensional image processing at high speed have been increasingly utilized. In a conventional two-dimensional graphics drawing apparatus, two-dimensional graphics data is used which does not include Z-values as depth information. In the case where a three-dimensional graphics drawing apparatus is to use the two-dimensional graphics data as utilized in the conventional two-dimensional graphics drawing apparatus to draw three-dimensional graphics, operations including rotation of drawing object coordinates and others must be done to convert the two-dimensional graphics data to three-dimensional graphics data before being able to perform oblique projection as in a bird""s-eye view.
Such operations for rotation of the drawing object coordinates and others, however, require a considerable amount of calculations, which decreases the drawing speed.
An object of the present invention is to provide an apparatus and a method for drawing three-dimensional graphics that allow high-speed conversion of two-dimensional polygon data to three-dimensional polygon data.
Another object of the present invention is to provide a recording medium that records three-dimensional polygon data generated from two-dimensional polygon data to allow a three-dimensional graphics drawing apparatus to draw three-dimensional graphics at high speed.
According to an aspect of the present invention, the three-dimensional graphics drawing apparatus includes: a converting unit that converts two-dimensional polygon data to three-dimensional polygon data by substituting an X-coordinate value of the two-dimensional polygon data for an X-coordinate value of the three-dimensional polygon data, substituting a Y-coordinate value of the two-dimensional polygon data for a Z-coordinate value of the three-dimensional polygon data, and substituting a prescribed value for a Y-coordinate value of the three-dimensional polygon data; and a drawing unit that draws three-dimensional graphics according to the three-dimensional polygon data generated by the converting unit.
Since the converting unit generates the three-dimensional polygon data from the two-dimensional polygon data exclusively by simple substitutions of the coordinate values, complicated operations become unnecessary for generation of the three-dimensional polygon data. Accordingly, the three-dimensional graphics drawing apparatus is able to draw the three-dimensional graphics at high speed.
According to another aspect of the present invention, the three-dimensional graphics drawing method includes: a step of converting two-dimensional polygon data to three-dimensional polygon data by substituting an X-coordinate value of the two-dimensional polygon data for an X-coordinate value of the three-dimensional polygon data, substituting a Y-coordinate value of the two-dimensional polygon data for a Z-coordinate value of the three-dimensional polygon data, and substituting a prescribed value for a Y-coordinate value of the three-dimensional polygon data; and a step of drawing three-dimensional graphics according to the generated three-dimensional polygon data.
Since the three-dimensional polygon data is generated from the two-dimensional polygon data only with simple substitutions of the coordinate values, complicated operations are unnecessary for generating the three-dimensional polygon data. Accordingly, it becomes possible to draw the three-dimensional graphics at high speed.
According to a further aspect of the present invention, the computer readable recording medium records three-dimensional polygon data generated from two-dimensional polygon data. The three-dimensional polygon data includes a plurality of three-dimensional polygon data, each of which has an X-coordinate value of the two-dimensional polygon data substituted for an X-coordinate value of the three-dimensional polygon data, a Y-coordinate value of the two-dimensional polygon data substituted for a Z-coordinate value of the three-dimensional polygon data, and a prescribed value substituted for a Y-coordinate value of the three-dimensional polygon data.
Accordingly, it becomes possible to use a conventional three-dimensional graphics drawing apparatus, without modification, to draw the three-dimensional graphics at high speed.